Khaled Asaad was a bespectacled scholar who had devoted more than five decades of his life to preserving the ruins of Palmyra, a majestic 2,000-year-old city in the Syrian desert.

On Tuesday he was beheaded by Islamic State extremists, his body left to hang from one of the stone columns in the ancient city’s central square, activist groups and officials told reporters, according to the AP and Reuters.

Palmyra was captured by Islamic State this May, prompting fears that the jihadists would destroy the UNESCO world heritage site about 130 miles northeast of Damascus. The group has demolished ancient landmarks and looted cultural treasures throughout the swaths of Syria and Iraq under its control — experts say that pre-Islamic artifacts and symbols of multiculturalism are considered sacrilegious by the Islamic State’s puritanical interpretation of Islam.

In June, the militants blew up two of Palmyra’s ancient shrines that were not part of its Roman-era ruins, but there is no other evidence that the rest of the heritage site has been ransacked. Instead, the group’s violence in the area has been directed toward people, like the 82-year-old Asaad.

The U.K.-based Syrian Observatory for Human Rights told the Associated Press that Asaad was killed in a square outside the modern town’s museum. His body was then taken to the ruins of the ancient city.

“Just imagine that such a scholar who gave such memorable services to the place and to history would be beheaded … and his corpse still hanging from one of the ancient columns in the center of a square in Palmyra,” Syrian state antiquities chief Maamoun Abdulkarim told Reuters. “The continued presence of these criminals in this city is a curse and bad omen on [Palmyra] and every column and every archaeological piece in it.”

According to Abdulkarim, Asaad had been detained and interrogated by militants for more than a month before he was killed.

Asaad has authored scholarly works on Palmyra, where he served as head of antiquities. Abdulkarim told Reuters that he also worked with American, French, German and Swiss archaeological missions to excavate and research the city’s ancient tombs and temples.